Axis convertee



June 29, 1954 E. E. LIBMAN 2,682,370

AXIS CONVERTER Filed June 5, 1950 2 Sheets-Sheet l mmvron. Earl E. Lbmwn,

June 29, 1954 L|BMAN 2,682,370

AXIS CONVERTER Filed June 5, 1950 2 Sheets-Sheet 2 77 cf 1 I 86' 7% w ar a 4 INIfENTOR. fi'azllilzbmauz,

BYW/KM Patented June 29, 1954 UNITED STATES PATENT OFFICE AXIS CONVERTEREarl E. Libman, Brooklyn, N. Y., assignor to Con trol InstrumentCompany, Ina, Brooklyn, N. Y., a corporation of New York ApplicationJune 5, 1950, Serial No. 166,191

10 Claims. 1

This invention relates to improvements in mechanisms employed inpositioning guns and has particular reference to an axis converter foruse with air-borne guns.

With a gun mounted in the nose structure or turret of a militaryaircraft, it is frequently necessary, in order to hit a target, torotate a part of said structure relative to the fore and aft axis of theaircraft and, additionally, to incline the gun to said axis. Therotation about this axis is known as roll and the inclination of the gunis called traverse.

The computer that determines the position the gun should assume in orderto hit a target, is ordinarily of the type that computes said positionin terms of the spherical coordinates of azimuth and elevation, theformer being the angle of rotation of the gun about a vertical axis andthe elevation being an angle between the gun and a horizontal plane.When thus computed in terms of azimuth and elevation, it is necessary toconvert the gun position data received from the computer into terms ofroll and traverse, such step being known as axis conversion. Heretofore,the construction of axis converters often resulted in mechanisms thatfunctioned over only a part of the desired firing area and locked up,mechanically, in other parts of said area, and structural supports orthe like also prevented motion of elements of the mechanisms andtherefore limited the range of operation thereof.

An object of the present invention is to provide an improved controlmechanism of practical construction and positive operation which willconvert input data of azimuth and elevation into data of roll andtraverse, and wherein. complete freedom of movement of elements of themechanism within the desired range of operation of the device will beattained.

The above and other objects will appear more clearly from the followingdetailed description when taken in connection with the accompanyingdrawings which illustrate a preferred embodiment of the inventive idea;but it will be ex pressly understood that said drawings are employedmerely for the purpose of facilitating the description of the inventionas a whole and not to define the limits thereof, reference being had tothe appended claims for this purpose.

In the drawings:

Fig. l is a diagrammatic view showing the relative positions of thetarget and the gun, and the spherical coordinates representing theangles of azimuth and elevation;

. positionable elements of the mechanism; and

Fig. 6 is a diagrammatic view of the electrical circuits employed inconnection with the mechanism shown inFig. 2.

Referring to Fig. 1, when an aircraft at the point 0 with fore and aftaXis O-O' sights a target, a computer or director predicts the direction0'? along which gunfire is to be directed and gives this gun directionin spherical coordinates relative to the point 0, as the angles B and E.B is the angle of train O'OPz and E1 is the angle of elevation PzOP',and these represent, respectively, the angle in the horizontal planethrough the ships fore and aft axis in which the gun should be trained,and the angle to said horizontal plane throughwhich the gun should beraised or lowered in elevation. Thus, the gun will be directed along thepredicted direction OP.

As has been pointed out, some air-borne guns are not free to move intrain and elevation but must be directed by motions of traverse androll. A gun directed so as to possess the train and elevation angles Band E, respectively, has the roll and traverse angles PiOP'and OOP,respectively, so that the gun can be made to assume a desired directionOP either by positioning it by train and elevation angles or by itscorrespondingroll and traverse angles depending upon the mounting of thegun.

As shown in Fig. 2, the device embodying the features of the presentinvention comprises a base 8 to which is attached a difierential housing9 and which supports a standard ill having a laterally extending bracketI l at its upper end. A sleeve 12 extends horizontally from one side ofthe standard It, and plates 13 and Hi extending similarly from the otherside thereof provide a differential housing similar to the housing 9.Said housing 9, the standard I!) and its bracket ll combine to form asupport for the moving members of the converter mechanism.

Journaled at IS in the bracket ll and at it in 3 the upper portion ofthe housing 9 is a hollow arcuate guide member I? of rectangular crosssection (Fig. 3) mounted for rotation about a vertical axis, the degreeof its rotation being limited only by contact thereof with the bearingsleeve 12 and therefore being considerably in excess of 180. The upperbearing has a stud shaft l8 extending through the bracket II and securedin place by a nut IS. The lower bearing I6 is flanged at 20 to form asupport for the member I1, and said bearing is provided at its lower endwithin the housing 9 with a bevel gear 2| driven by a similar gear 22 onthe input shaft 23 so that said member I] may be rotated in train aboutits axis. The shaft 23 may be connected to a computer or director so asto be rotated thereby and thus convey to the member I! the proper angleof train.

The inner face of the member I? is slotted at Ha substantiallythroughout its entire length to allow the passage therethrough of asupporting rod 24 carrying at its outer end a soft iron disc 26, withsaid rod secured at its inner end to the carriage 25 that is capable ofmovement on its rollers 25a from either end to the other of the memberI! thus encompassing a movement of approximately 270. This movement ofthe carriage 25 is accomplished by means of cables 2'! and 28 (Fig. 5)which have their ends secured to the carriage and which pass over theguiding studs 29 and around the idler pulley 35 and the driving spindle3|, with said cables wound in opposite directions around said spindle sothat as one is wound thereon the other is unwound therefrom to permitthe carriage to be moved along its track formed by the inner face of themember I1 and thus be positioned at any point therein. The drivingspindle 3| carries the gear 32 meshing with the gear 33 on the shaft 34journaled in the flange 20, and said shaft is provided with a secondgear 35 engaged by a gear 35 on one end of the shaft 31 also journaledin said flange and in the bearing 15 (Fig. 2). At the other end of theshaft 31 within the bearing it, a crown gear 38 meshes with the pinion39 on the latter shaft, and said gear 38 is carried by a shaft 40 thatis driven by the gears 4|, 42, the latter being carried by the inputshaft 43 which, like the shaft 23, may also be connected to a computeror director and which is rotated to position the carriage 25 inelevation. When the member [1 and its mounting 20 are rotated by theshaft 23, any tendency of this rotation to impart movement to thecarriage 25 by reason of the rolling action of the pinion 39 on thecrown gear 38 is counteracted by the unwinding eifect of thedifferential mechanism supported within the housing 9. Said differentialincludes the gears 44 and 41 fixed to rotate with the gears 2| and 4|,respectively, and have the gears 45, 46 meshing therewith. Thus, withthe shaft 25 rotating to drive the gears 2| and 44 and with the gears 4|and 41 stationary by reason of the non-rotation of shaft 43, thedifferential will effect rotation of the shaft 40 and its gear 38 tocounteract the tendency of the shaft 31 to rotate in its bearings whileit is turning with the member about the vertical axis of the latter.

The member i1 is positioned according to the angle of azimuth byrotating the shaft 23 proportionally to that angle, and the carriage 25,with the disc 26 carried thereby, is moved along the member I! byrotating the shaft 43 through an angle proportional to the angle ofelevation. Thus, the magnetic disc 26 may be positioned ac- 4 cording tothe angles of train and elevation received by shafts 23 and 43,respectively.

The input data representing train and elevation on shafts 23 and 43which control the position of the member I! and carriage 25 is convertedinto output data of roll and traverse in the manner that will now bedescribed. The sleeve 12 supported by the standard H] has a hollow shaft48 extending therethrough which, as seen in Fig. 3, has an extension 49secured thereto. This extension carries a pin 50 projecting therefromupon which the gear 5| is free to rotate, and said gear carries theservo arm 52 associated with the magnetic disc 26 in a manner presentlyto be described. The pin 50 is located so that the center line 53therethrough will intersect the line 54 through the center of the sleeve|2 at the point 55 which lies at the center of the sphere which isgenerated by the rotation of the member I! on its axis. Within the shaft48 there is journaled a second shaft 56 that is free to be rotatedrelative to the shaft 48 and which carries a gear 51 meshing with thegear 5!. The outer shaft 48 is driven by the gear 58 from the shaft 59and gears 69, 5| connected to the two-phase motor 62. The inner shaft 56is driven by the gear 63 meshing with the gear 64 on the shaft 65 whichis operated by the gears 66, 6! coupled to the two-phase motor 58.Operation of the motors 62 and 68 is controlled in a manner to laterappear.

When the motor 68 is driven, the shaft 55 causes the arm 52 to be turnedin an are about the pin 50 as an axis to select the angle of traversethat said arm will occupy, and operation of the motor 62 will effectrotation of the shaft 48 to roll the gear 5| about the axis of the gear51 and thus select the angle of roll which said arm is to occupy. Inorder that the coordinate movements of the arm 52 may be properlyeffected by the two drives from the motors 52 and 63, said drives areinterconnected by a differential mounted within the housing formed bythe plates l3 and I4 and which functions in the same manner as thedifferential previously described in conjunction with the input shafts2'3 and 43.

Said differential comprises the gears H and i9 fixed, respectively, tothe gears 63 and 69 and meshing with the idler gears 10 and I2.Positioning the arm 52 so that the arm is directed at the magneticmember 26 involves displacing said arm in traverse and rotating it inroll, and thus the rotation of the driving motors 82 and 68 will beproportional to the angles of roll and traverse, respectively.

In order that the motors may be energized so that the arm 52 will trackwith and be maintained constantly directed toward the magnetic disc 26,said arm is provided at its free end with a lateral extension 14 towhich is secured a plate 14a including four equidistantly spaced arms(Fig. 4). Said plate carries five identical coils l5, 16, 11, I8 and 19having iron cores, with the energizing coil 15 disposed centrally of theplate and the remaining pick-up coils being arranged at the extremitiesof the arms of said plate. The distance between opposed extremities ofthe arms of said plate 14a is less than the diameter of the disc 26, andan air gap is provided between the outer extremity of the coils and saiddisc.

As will be seen from Fig. 6, the energizing coil 15 is connected to andconstantly energized by leads and 8| connected to a source ofalternating voltage L and said coil will thus generate an alternatingmagnetic field which will be conducted by the disc 26 and induce equalvoltages in each of the pick-up coils I6, 11, I8 and I9 when they aresymmetrically positioned with respect to said disc. Coils II and I9,which may be called the traverse coils, are interconnected, by means oflead 82, so that their voltages are opposed to each other and the sum ofthese voltages, when the voltage output of each of the coils is thesame, is zero. The sum voltage of the coils I1 and I9 is connected byleads 83 and 84 to the amplifier 95 which, by way of leads 80, BI, isenergized from the line L. The output voltage of the amplifier 85 on theleads 86 and 81 is connected to one phase of the two phase motor 68whose remaining phase is returned to the line L. Coils I6 and I8, whichmay be called the roll coils, are connected by. a lead 88 and the sum oftheir opposed output voltages in the leads 69 and 90 is fed to theamplifier 9| which is also energized from the line L. Output voltage ofthe amplifier 9| on leads 92 and 93 is then used to energize one phaseof the two-phase motor 62 whose remaining phase is energized from theline L.

Any new inputs of azimuth and elevation introduced into the mechanismfrom the shafts 23 and 43 will, by the resultant movements of themembers [I and 25, displace the position of the disc 26 to correspond tothe new inputs. disc is so displaced, the coil structure I5 to I9 willmomentarily be non-symmetrically disposed with respect to said disc andthe voltages representing the sum of the coiled pairs will no longer beequal to zero in view of the fact that the reluctance of the magneticpath between the energizing coil I5 and the pick-up coils I6 to I9 willdiffer. This difference voltage will energize the appropriate motor 62or 68 so that the arm 52 will be driven to correspondence with, or inexact positional relation to, the disc 26, whereupon the motors willstop and the position of the motor shafts 94, 95 may then be read as thenew angles of traverse and roll which correspond to the new inputcoordinates of elevation and azimuth.

From the foregoing, it will be seen that the invention provides amechanism which will be responsive to both inputs of azimuth andelevation and will convert them into roll and traverse by thedisplacement of the disc 26 relative to the associated coil structure sothat the servo arm 52 will move about its roll axis and through atraverse angle to maintain alignment of said disc and arm, and that themechanism is so constituted that there is no null at which said arm willfail to follow said disc or any position from which the arm cannot move.

With previous devices of this nature, as well as with gun mounts whichhave only two degrees of freedom, 1. e. in which the gun is mounted intrunnions which are rotatable about a vertical axis thru the center ofthe gun mount, there exists a point (the null mentioned above) at whichthe gun mount or the converting mechanism is in a locked position. Sucha position would be one similar to the position (Fig. 2) of arm 52 if itwere extended to the right directly in line with the axis of shaft 56and if its outer end, upon which the coils 11, etc. are mounted wererigidly attached to the magnetic disc 29. In such a position as this,and under the above condition, if an attempt were made to rotate thesector II, no movement would be possible for the tendency would be tobend the arm 52. This would be the case with an axis converter whichmight have an As the arm equivalent to the present arm 52 but rigidlyattached to the equivalent of the present trolly mechanism 26, etc.

This invention overcomes thisdifficulty, as has been generally pointedout above, by keeping the arm 52 separated from the trolly mechanism butelectro-magnetically coupled to it. Thus, when the arm 52 reaches aposition directly to the right as seen in Fig. 2 in which it islongitudinally aligned with shaft 56, if it is desired to move thesegment H, such a motion may be completed Without resistance. The arm 52will then follow the trolly mechanism because of the particulararrangement of the pickup coils I6-'I9, inclusive. Under the aboveconditions, when the sector II is rotated moving the trolly 25-26, etc.arcuately away from the traverse coils II and I9, the coil systembecomes unbalanced as to roll coils I6 and I8, that is to say, ifsegment I! rotates in such fashion that the magnetic disc 26 moves awayfrom the observer as seen in Fig. 2 and parallel to a center line commonto the roll coils I6 and I8, the effect will be to diminish the currentof coil I8 and to increase the current ofcoi1 I6 leaving the currents oftraverse coils I1 and I9 diminished but equal to each other. Thiscondition, through amplifier M, (Fig. 6) will immediately cause rollmotor 62 to turn the arm 52 about its longitudinal axis. When thisoccurs, the arm 52 will immediately be free to follow the disc 26 andthus attain its proper position according to the new input. It is to beparticularly noted that since the gun contemplated in conjunction withthe present invention is mounted for rotation about two axes and twoaxes only, its action will be precisely the action of arm 52 which maybe considered to be a dummy gun. This means that the gun itself willroll with the arm 52 and then follow said arm in traverse.

From the foregoing, it is seen that the present invention provides ameans of eliminating the usual null or looking position of a gun whichis mounted for rotation about two axes at right angles to each other andthat it further provides an axis converting mechanism having a dummy gunwhich is followed in movement precisely by the real gun.

It is further to be understood that the word null as hereinbeforementioned means thatcondition of a gun or similar object, mounted in theusual pair of trunnions for rotation about an axis through a center linecommon to both trunnions which trunnions are rotatable in a planeparallel to said axis, when the longitudinal axis of the gun and thetrunnion axis lie in a plane perpendicular to the aforementioned planeand when it is attempted to move the gun in the last mentioned plane.this condition would occur when the gun pointed straight up away fromthe center of the earth, and would occur in the nose gun of a plane whenthe longitudinal axis of the gun coincided with the longitudinal axis ofthe body of the aircraft.

What is claimed is:

1. In an axis converter mechanism for guns, input means thereforresponsive to data of azimuth and elevation, output means for saidmechanism identifying data of roll and traverse, meansoperativelyconnected to said input and output means and controlled bysaidinput means to convert said data of azimuth and elevation into dataof roll and traverse and to transmit the latter data to said outputmeans, said operative means including cooperating members eachcontrolled by one of said input means and one supported y In an ordinarydeck gun on shipboard,

the other and having movement about diiferent axes to describe arcuatepaths both in excess of 180, the resultant of said movements indicatin adirection, a device operatively associated with said members andincluding a magnetic element carried by one of said members, a coilstructure coacting with said magnetic element in opposed spaced relationthereto and influenced by variations in the reluctance between saidelement and the coils of said structure created by movement of saidmembers relative to said coils to maintain said opposed relationship,and connections between said coil structure and said output means foroperating the latter in accordance with the direction indicated by themovements of said members.

2. In an axis converter mechanism for guns, input means thereforresponsive to data of azimuth and elevation, output means for saidmechanism identifying data of roll and traverse, means operativelyconnected to said input and output means and controlled by said inputmeans to convert said data of azimuth and elevation into data of rolland traverse and to transmit the latter data to said output means, saidoperative means including cooperating members each controlled by one ofsaid input means and one supported by the other and having movementsabout difierent axes to describe arcuate paths both in excess of 180,the resultant of said movements indicatin a direction, a deviceoperatively associated with said members and including a magneticelement carried by one of said members, a coil structure including acentral energizing coil and a plurality of pick-up coils arrangedsymmetrically about said energizing coil and relative to said magneticelement, said coils coacting with said magnetic element in opposedrelation thereto and controlled by variations in the reluctance betweensaid element and the pick-up coils of said structure created by movementof said members relative to said coils to maintain said opposedrelationship, an arm supporting said coil struc ture and havingmovements about two different axes, driving means for said output meanscoupled to said arm and controlled by said variations in reluctance todrive said output means and to move said arm about its axes inaccordance with the resultant movements of the first named cooperatingmembers.

3. In an axis converter mechanism for guns, input and output means forsaid mechanism, two driving means for said output means, a supportingstructure for said mechanism, a sleeve member extendin laterally fromsaid supporting structure, inner and outer shafts journalled in saidsleeve member and each coupled to one of said driving means, an armconnected to one of said shafts for rotative movement about the axisthereof, gearing coupling the other shaft to said arm for rotating thesame about a different axis, an arcuate member mounted in saidsupporting structure for rotative movement therein limited only bycontact of said arcuate member with said sleeve member, operativeconnections between one of said input means and said arcuate member, acarriage mounted in said arcuate member for movement therewith and alsomovement relative thereto in an arcuate path in excess of 180, operativeconnections between the other input means and said carriage for movingthe latter relative to saidarcuate member, a magnetic element mounted onsaid carriage for movement therewith, a coil structure carried by saidarm in opposed and spaced relation to said magnetic element andincluding a plurality of pick-up coils symmetrically arranged relativeto said magnetic element, and means connecting said pick-up coils withsaid driving means to operate the latter upon variation in thereluctance between said magnetic element and said coils.

4. A servo mechanism for use in an axis converter wherein two membersare movable about difierent axes, said mechanism comprising a deviceoperatively associated with said members and includin a magnetic elementcarried by one of them, a coil structure including a central energizingcoil and a plurality of pick-up rolls arranged symmetrically about saidenergizin coil and relative to said magnetic element, said coilscoacting with said magnetic element in opposed relation thereto andcontrolled by variations in the reluctance between said element andpick-up coils created by movement of said members relative to said coilsto maintain said opposed relationship, means to support said coilstructure and having movements about different axes, and meanscontrolled by said variations in reluctance to move said structuresupporting means about its axes.

5. In an axis converter wherein two members are movable about diilerentaxes, an arm having movements about different axes, a device operativelyassociated with said members and includin means positioned in opposedrelationship to said arm, means on said arm to electro-magneticallycouple said arm to said opposed means to move said arm about its axes inresponse to movement of said members.

6. In an axis converter wherein two members are movable about differentaxes, a device operatively associated with said members, an arm, meansoperable to r011 said arm about one axis, means operable to move saidarm traversely about another axis, electro-magnetic coupling means onand between said arm and said device including a pair of roll coils anda pair of traverse coils, said roll means and said traverse means beincontrolled by variations in reluctance between said roll and traversecoils respectively and said device to move said arm about its diiferentaxes.

'7. In an axis converter wherein two members are movable about differentaxes, a device operatively associated with said members and includlllg amagnetic means carried by one of them, a coil structure including a pairof roll coils, an energizing coil for inducing equal voltages in saidroll coils, said voltages in said roll coils varying in response tomovement of said magnetic means, means for supplying pulsating currentto said energizing coil, means under control of said roll I coils forindicating the coordinate of roll, and means supporting said coilstructure having said energizing coil, said coils coacting with saidmagnetic means in opposed relation thereto and controlled by variationsin the reluctance between said magnetic means and coils created bymovement of said members relative to said coils to maintain said opposedrelationship, and means to support said coil structure having movementsabout difierent axes in response to the variations in reluctance.

9. In an axis converter wherein two members are movable about differentaxes, a device operatively associated with said members and including amagnetic means, a coil structure comprising a pair of traverse coils, anenergizing coil for inducing equal voltages in said traverse coils, saidcoils coacting with said magnetic means in opposed relation thereto andcontrolled by variations in the reluctance between said means andtraverse coils created by movement of said members relative to saidcoils to maintain said opposed. relationship and means to'support saidcoil structure having movements about different axes and movedtraversely in response to the variations in reluctance.

10. In an axis converter wherein two members are movable about differentaxes, a device operatively associated with said members and including amagnetic means, a coil structure comprising a pair of roll coils, a pairof traverse coils, an energizing coil for said pairs of coils forinducing equal voltages in said roll coils and said traverse coils,means for supplying pulsating current to said energizing coil, saidcoils coacting with said magnetic means and controlled by variations in10 the reluctance between said magnetic means and said coils created bymovement of said members relative to said coils, means to support saidcoil structure, said support means having movements about diiiferentaxes in response to the variations in reluctance.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,751,649 Nieman Mar. 25, 1930 1,880,174 Dugan Sept. 27, 19322,069,417 Murtaugh Feb. 2, 1937 2,094,039 Kinsley Sept. 28, 19372,339,508 Newell Jan. 18, 1944 2,399,675 Hays May 7, 1946 2,462,081Esval Feb. 22, 1949 2,492,244 Shivers Dec. 27, 1949 2,586,817 HarrisFeb. 26, 1952 FOREIGN PATENTS Number Country Date 204,661 SwitzerlandAug. 1, 1939 366,076 Great Britain Jan. 29, 1932 421,315

Great Britain Dec. 18, 1934

